1. Technical Field of the Invention
This invention relates to an industrial robot that suspends a suspended unit movably in a straight line on a straight axis that is fixed on a stationary part.
2. Description of the Related Art
In the case where an industrial robot is introduced into a small installation, a perpendicularly intersected type industrial robot is used. This type of the industrial robot has two straight-moving axes that are perpendicularly intersected.
By the way, since a space just under the straight-moving axes is a useless space (or so-called dead space) instead of a workspace in the perpendicularly intersected type industrial robot, it is effective to replace the perpendicularly-intersected type industrial robot having a composition with a suspended unit being suspended on a straight axis.
That is, an effective use of the space just under the straight axis can be attained by suspending a suspended unit as shown in a Japanese Patent Application Laid-Open Publication No. 59-129677 to a straight-moving industrial robot as shown in a Japanese Patent Application Laid-Open Publication No. 54-118056, for example.
However, since the suspended unit is constituted by arranging a drive source and a movable member in the height direction, with the composition that only suspends the suspended unit to the straight axis, the height size of the suspended unit becomes large and thus the whole robot system becomes large.